1. Field of the Invention
The present invention relates to a punching device for punching holes in a thin member, e.g., a board or a plate such as a wooden board or an iron plate, or a sheet of some material, a sheet processor having the punching device provided in its main body, and an image forming apparatus also having the punching device provided in its main body.
2. Related Background Art
Conventionally, punching devices have been used singly or as a component in a state of being incorporated in an apparatus with which a thin member to be punched is handled.
For example, an application of a punching device in a sheet processor for binding or folding punched sheets is known. The punching device is used in a state of being incorporated in the main body of the sheet processor. An application of a punching device in an image forming apparatus such as a copying machine, a laser beam printer, a facsimile machine, or a combination of some of these apparatuses is known. The punching device is used as a component in a state of being incorporated in a main body of the image forming apparatus. Further, in some cases, a punching device is used in a state of being incorporated in a sheet processor and incorporated in a main body of an image forming apparatus together with the sheet processor.
A punching device used to make holes in a member has the number of punches and the same number of dies corresponding to a certain number of holes which should be made in the member by punching. The punching device punches holes in the member by causing each punch to advance into the hole in the corresponding die.
Conventional punching devices, however, have a complicated mechanism for operating each punch and are therefore incapable of punching holes in a member smoothly and quickly.
In recent years, there has been an increasing demand for changing the number of holes to be punched in a member in accordance with the size thereof. It is not possible to satisfy the demand by using any of the conventional punching devices since each conventional punching device has only punches and dies corresponding to the number of holes to be punched in a member.